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.TH EXIT 2 "Feb 5, 2008"
.SH NAME
exit, _Exit, _exit \- terminate process
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>

\fBvoid\fR \fBexit\fR(\fBint\fR \fIstatus\fR);
.fi

.LP
.nf
\fBvoid\fR \fB_Exit\fR(\fBint\fR \fIstatus\fR);
.fi

.LP
.nf
#include <unistd.h>

\fBvoid\fR \fB_exit\fR(\fBint\fR \fIstatus\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBexit()\fR function first calls all functions registered by
\fBatexit\fR(3C), in the reverse order of their registration, except that a
function is called after any previously registered functions that had already
been called at the time it was registered. Each function is called as many
times as it was registered. If, during the call to any such function, a call to
the \fBlongjmp\fR(3C) function is made that would terminate the call to the
registered function, the behavior is undefined.
.sp
.LP
If a function registered by a call to \fBatexit\fR(3C) fails to return, the
remaining registered functions are not called and the rest of the \fBexit()\fR
processing is not completed. If \fBexit()\fR is called more than once, the
effects are undefined.
.sp
.LP
The \fBexit()\fR function then flushes all open streams with unwritten buffered
data, closes all open streams, and removes all files created by
\fBtmpfile\fR(3C).
.sp
.LP
The \fB_Exit()\fR and \fB_exit()\fR functions are functionally equivalent. They
do not call functions registered with \fBatexit()\fR, do not call any
registered signal handlers, and do not flush open streams.
.sp
.LP
The \fB_exit()\fR, \fB_Exit()\fR, and \fBexit()\fR functions terminate the
calling process with the following consequences:
.RS +4
.TP
.ie t \(bu
.el o
All of the file descriptors, directory streams, conversion descriptors and
message catalogue descriptors open in the calling process are closed.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the parent process of the calling process is executing a \fBwait\fR(3C),
\fBwait3\fR(3C), \fBwaitid\fR(2), or \fBwaitpid\fR(3C), and has neither set its
\fBSA_NOCLDWAIT\fR flag nor set \fBSIGCHLD\fR to \fBSIG_IGN\fR, it is notified
of the calling process's termination and the low-order eight bits (that is,
bits 0377) of \fIstatus\fR are made available to it.  If the parent is not
waiting, the child's status will be made available to it when the parent
subsequently executes \fBwait()\fR, \fBwait3()\fR, \fBwaitid()\fR, or
\fBwaitpid()\fR.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the parent process of the calling process is not executing a \fBwait()\fR,
\fBwait3()\fR, \fBwaitid()\fR, or \fBwaitpid()\fR, and has not set its
\fBSA_NOCLDWAIT\fR flag, or set \fBSIGCHLD\fR to \fBSIG_IGN\fR, the calling
process is transformed into a \fIzombie process\fR. A \fIzombie process\fR is
an inactive process and it will be deleted at some later time when its parent
process executes \fBwait()\fR, \fBwait3()\fR, \fBwaitid()\fR, or
\fBwaitpid()\fR. A zombie process only occupies a slot in the process table; it
has no other space allocated either in user or kernel space. The process table
slot that it occupies is partially overlaid with time accounting information
(see \fB<sys/proc.h>\fR) to be used by the \fBtimes\fR(2) function.
.RE
.RS +4
.TP
.ie t \(bu
.el o
Termination of a process does not directly terminate its children. The sending
of a \fBSIGHUP\fR signal as described below indirectly terminates children in
some circumstances.
.RE
.RS +4
.TP
.ie t \(bu
.el o
A \fBSIGCHLD\fR will be sent to the parent process.
.RE
.RS +4
.TP
.ie t \(bu
.el o
The parent process \fBID\fR of all of the calling process's existing child
processes and zombie processes is set to 1. That is, these processes are
inherited by the initialization process (see \fBIntro\fR(2)).
.RE
.RS +4
.TP
.ie t \(bu
.el o
Each mapped memory object is unmapped.
.RE
.RS +4
.TP
.ie t \(bu
.el o
Each attached shared-memory segment is detached and the value of
\fBshm_nattch\fR (see \fBshmget\fR(2)) in the data structure associated with
its shared memory \fBID\fR is decremented by 1.
.RE
.RS +4
.TP
.ie t \(bu
.el o
For each semaphore for which the calling process has set a \fBsemadj\fR value
(see \fBsemop\fR(2)), that value is added to the \fBsemval\fR of the specified
semaphore.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the process is a controlling process, the \fBSIGHUP\fR signal will be sent
to each process in the foreground process group of the controlling terminal
belonging to the calling process.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the process is a controlling process, the controlling terminal associated
with the session is disassociated from the session, allowing it to be acquired
by a new controlling process.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the exit of the process causes a process group to become orphaned, and if
any member of the newly-orphaned process group is stopped, then a \fBSIGHUP\fR
signal followed by a \fBSIGCONT\fR signal will be sent to each process in the
newly-orphaned process group.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the parent process has set its \fBSA_NOCLDWAIT\fR flag, or set \fBSIGCHLD\fR
to \fBSIG_IGN\fR, the status will be discarded, and the lifetime of the calling
process will end immediately.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the process has process, text or data locks, an \fBUNLOCK\fR is performed
(see \fBplock\fR(3C) and \fBmemcntl\fR(2)).
.RE
.RS +4
.TP
.ie t \(bu
.el o
All open named semaphores in the process are closed as if by appropriate calls
to \fBsem_close\fR(3C). All open message queues in the process are closed as if
by appropriate calls to \fBmq_close\fR(3C). Any outstanding asynchronous I/O
operations may be cancelled.
.RE
.RS +4
.TP
.ie t \(bu
.el o
An accounting record is written on the accounting file if the system's
accounting routine is enabled (see \fBacct\fR(2)).
.RE
.RS +4
.TP
.ie t \(bu
.el o
An extended accounting record is written to the extended process accounting
file if the system's extended process accounting facility is enabled (see
\fBacctadm\fR(8)).
.RE
.RS +4
.TP
.ie t \(bu
.el o
If the current process is the last process within its task and if the system's
extended task accounting facility is enabled (see \fBacctadm\fR(8)), an
extended accounting record is written to the extended task accounting file.
.RE
.SH RETURN VALUES
.sp
.LP
These functions do not return.
.SH ERRORS
.sp
.LP
No errors are defined.
.SH USAGE
.sp
.LP
Normally applications should use \fBexit()\fR rather than \fB_exit()\fR.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	See below.
_
Standard	See \fBstandards\fR(7).
.TE

.sp
.LP
The \fB_exit()\fR and \fB_Exit()\fR functions are Async-Signal-Safe.
.SH SEE ALSO
.sp
.LP
.BR Intro (2),
.BR acct (2),
.BR close (2),
.BR memcntl (2),
.BR semop (2),
.BR shmget (2),
.BR sigaction (2),
.BR times (2),
.BR waitid (2),
.BR atexit (3C),
.BR fclose (3C),
.BR mq_close (3C),
.BR plock (3C),
.BR tmpfile (3C),
.BR wait (3C),
.BR wait3 (3C),
.BR waitpid (3C),
.BR signal.h (3HEAD),
.BR attributes (7),
.BR standards (7),
.BR acctadm (8)
